So called infotainment (i.e. movies, music, news information, etc.) is offered for the entertainment of passengers in aircraft, in particular passenger airplanes. This multimedia infotainment content may be available to passengers during a flight, for example, on mobile terminals such as tablet PCs or smartphones, for example. The proprietors of rights in the infotainment content normally only grant usage rights to the content (e.g. movies, music items, etc.) for a clearly limited scope of use. For example, said scope of use may have temporal (e.g. a time window), spatial (e.g. region, language, etc.) and/or situational (e.g. for cinema, home TV, mobile use, use by an airline, etc.) limitations. Provision is therefore made for special usage rights such as e.g. the so-called “Airline Hospitality Window” in relation to infotainment content that is to be used in an aircraft, such usage rights being required in order to use this relatively new infotainment content while using an aircraft or a flight.
Various means of using infotainment content in aircraft, in particular passenger airplanes, are known. One possibility is for mobile terminals containing previously downloaded infotainment content to be given to passengers on loan during a flight by the respective airline operator, or for passengers in the aircraft to be able to download infotainment content onto their own mobile terminals by means of so-called streaming from a streaming server which is installed in the aircraft. However, these two variants require a corresponding infrastructure and logistics on the part of the airline operator. A corresponding efficient and expensive infrastructure (e.g. server, mobile terminals, etc.) must be available in the airplane, and this infrastructure must be updated continuously for current infotainment content, wherein a large number of mobile terminals must be provided with new content or a large volume of data must be transferred onto the streaming server, for example.
The infotainment content can also be downloaded by the respective passenger onto their own mobile terminal already before using an airplane. For this purpose, infotainment content can be purchased in advance by a passenger and stored on their mobile terminal, wherein little or no content from the so-called “Airline Hospitality Window” is used for this purpose, and use is instead made of content that is e.g. accessible generally and e.g. available via the Internet or specific Internet sites. A further possibility is however provided by so-called buffered infotainment content. In this case, infotainment content is downloaded by the passenger e.g. from an airline-operated server onto their mobile terminal while on the ground and before using the aircraft, for example. The content can then be viewed with a time delay in the airplane. However, this variant of the infotainment content use only allows partial verification of the so-called “Airline Hospitality Window”, i.e. use in the airplane. While it is possible to check a temporal restriction relating to the use of the content, it is not possible to monitor regional or situational use of the content as part of limiting the usage rights to view the infotainment content during a flight, since it is not possible to establish whether the mobile terminal is actually in the aircraft. Therefore e.g. usage rights relating to use of content on the ground are applied in many cases, and consequently the available content is frequently out of date and/or subject to a regional usage restriction.
Although mobile terminals such as e.g. tablet PCs, smartphones, etc. now offer facilities and/or applications for position fixing, use thereof may be restricted or ineffective in an aircraft. The connection to the radio network is often used as a basis for fixing the position of a mobile terminal such as a cell phone, for example. However, this connection is deactivated for reasons of safety in an aircraft. In order to effect this deactivation, modern mobile terminals such as e.g. tablet PCs and smartphones can be switched into so-called flight mode, in which the connection and connection setup to a radio network is prevented.
However, these modern mobile terminals, which can also be used to play infotainment content, often have e.g. a facility and/or application by means of which satellite signals of a global navigation satellite system can be received and analyzed for the purpose of position fixing. In the case of satellite-based position fixing e.g. by means of GPS (Global Positioning System), three-dimensional position fixing of the mobile terminal nonetheless requires a distance from the mobile terminal to at least four visible navigation satellites to be ascertained. The distance between the relevant navigation satellites and the mobile terminal is then derived from a signal propagation time. Due to the screening effect of the airplane shell, reception of navigation satellite signals is however usually insufficient to allow position fixing of the mobile terminal in an aircraft.
In addition, mobile terminals such as e.g. tablet PCs, smartphones, etc. often lack full receivers for navigation satellite signals or GPS, and instead use a method called Assisted GPS. In this case, the mobile terminal simply takes propagation time measurements based on the receipt of so-called pseudoranges to a plurality of navigation satellites. The name pseudoranges is used because, due to a limited length of the sequences of the navigation satellite signals, the propagation time between the navigation satellites and the mobile terminal is only a modulo 1 ms value. For the purpose of position fixing, the navigation satellite signals must be supplemented by further information (so-called auxiliary data such as e.g. navigation data or orbital data of the satellites), which is supplied via the respective radio network or radio communication system in the case of Assisted GPS. However, this information is not available in an airplane because a connection to the radio network is not present or has been deactivated. Moreover, the navigation signals of the satellites in the airplane are severely attenuated or, for example, a sufficient number of navigation satellite signals for position fixing can seldom be received. At best, they may be available from a seat in the immediate vicinity of an airplane window.
For the purpose of validation for a subsequent journey by air, position fixing can be performed at a departure airport and then used. However, this procedure has the disadvantage that the position fixing is relatively unreliable and inaccurate for checking corresponding usage rights in relation to infotainment content which is only allowed to be used during a flight, for example. Although it can be established that a passenger is located at the departure airport with the relevant mobile terminal on which this specifically protected content will be used, it is not conclusively checked whether the corresponding flight is also used.
Further possibilities for determining a position of a mobile terminal in an aircraft, or checking whether a specific mobile terminal is located in a specific aircraft, consist in e.g. the aircraft providing amplification facilities (so-called repeaters) for navigation satellite signals or broadcasting current position data in the airplane via wireless LAN or Bluetooth, for example. In both cases, a dedicated and generally expensive infrastructure must be installed in the airplane in order that the position data can be supplied. In particular, specific cost-intensive precautions must be taken when using repeaters for the navigation satellite signals, since navigation satellite signals are very important to flight safety and therefore disruptions must be prevented.